1. Field of the Invention
The present invention relates to a plasma display panel (PDP).
2. Description of the Related Art
A PDP is a display device that realizes the display of images through the excitation of phosphors by plasma discharge. That is, vacuum ultraviolet (VUV) rays emitted from plasma obtained via gas discharge excite phosphor layers, which then emit visible red (R), green (G), and blue (B) light to thereby form images. The PDP has many advantages including an ability to be made having large screen sizes of 60 inches and greater, a thin profile of 10 cm or less, a wide viewing angle and good color reproduction due to the self-emissive nature of the PDP (as in the case of cathode-ray tubes), and high productivity and low manufacturing costs as a result of manufacturing processes that are more simple than those involved with liquid crystal displays. As a result, the PDP is experiencing increasingly widespread use in the home and in industry.
In the conventional alternating current (AC) PDP, a rear substrate and a front substrate are provided opposing one another with a predetermined gap therebetween. Formed on a surface of the rear substrate opposing the front substrate are a plurality of address electrodes. The address electrodes are formed in a stripe pattern along a first direction. A first dielectric layer is formed on the rear substrate covering the address electrodes, and a plurality of barrier ribs are formed on the first dielectric layer. The barrier ribs are typically formed in a stripe pattern along the first direction and at areas corresponding to between the address electrodes. R, G, and B phosphor layers are respectively formed between adjacent pairs of the barrier ribs.
Formed on a surface of the front substrate opposing the rear substrate are a plurality of display electrodes, which are realized through bus electrodes and opposing pairs of transparent electrodes. A second dielectric layer and an MgO protection layer are formed in this order on the front substrate covering the display electrodes.
Each area between one of the address electrodes and a pair of the display electrodes, and delimited by the intersection of these elements forms a discharge cell. A few hundred million discharge cells may be formed in a matrix configuration by this arrangement.
A memory characteristic is utilized to simultaneously drive the millions of discharge cells of the AC PDP. A potential difference of at least a predetermined voltage, referred to as a firing voltage Vf, is required to realize discharge between a sustain electrode and a scan electrode forming each pair of the display electrodes. If an address voltage Va is applied between one of the scan electrodes and one of the address electrodes, discharge is initiated such that plasma is created in a corresponding discharge cell. Electrons and ions in the plasma migrate toward the electrode of opposite polarity to thereby realize the flow of current.
With the formation of the first dielectric layer over the address electrodes, and the second dielectric layer over the display electrodes, most of the migrated space charges accumulate on the first and second dielectric layers, which are opposite in polarity. The result is that a net space potential between the scan electrodes and the address electrodes becomes less than the originally applied address voltage Va to weaken discharge and thereby terminate address discharge. A relatively small number of electrons accumulate toward the sustain electrodes, while a relatively large number of ions accumulate toward the scan electrodes. The charge accumulated on the second dielectric layer, which covers the sustain and scan electrodes, is referred to as a wall charge Qw, while the space voltage formed between the sustain and scan electrodes by the wall charge Qw is referred to as a wall voltage Vw.
Subsequently, if a predetermined discharge sustain voltage Vs is applied between the sustain and scan electrodes, and if a sum of the discharge sustain voltage Vs and the wall voltage Vw (Vs+Vw) becomes larger than the firing voltage Vf, discharge is effected in the corresponding discharge cells. VUV rays generated as a result excite the corresponding phosphor layer such that visible light is emitted through the transparent front substrate.
However, when there is no address discharge between the scan electrodes and the address electrodes (i.e., when there is no application of an address voltage Va), no wall charge is present between the sustain and scan electrodes, and, ultimately, no wall voltage between the same. Hence, only the discharge sustain voltage Vs that is applied between the sustain and scan electrodes is formed in the discharge cell, and since this voltage alone is smaller than the firing voltage Vf, no discharge occurs in the gaseous spaces of the sustain and scan electrodes.
In the PDP operating as described above, many steps are involved between power input and obtaining the display of visible light. Further, the efficiency of converting energy in each of these steps is low. The conventional CRT, in fact, has a better overall efficiency (brightness to power consumption ratio) than does the PDP. The low energy efficiency of conventional PDPs is a serious drawback of this display configuration.